Structures and methods for creating cavities in interior body regions

ABSTRACT

Tools carry structures that are deployed inside bone and, when manipulated, cut cancellous bone to form a cavity.

RELATED APPLICATIONS

[0001] This application is a divisional of application Ser. No.09/055,805, filed Apr. 6, 1998, and entitled “Structures and Methods forCreating Cavities in Interior Body Regions.”

FIELD OF THE INVENTION

[0002] The invention relates to structures and procedures, which, inuse, form cavities in interior body regions of humans and other animalsfor diagnostic or therapeutic purposes.

BACKGROUND OF THE INVENTION

[0003] Certain diagnostic or therapeutic procedures require theformation of a cavity in an interior body region.

[0004] For example, as disclosed in U.S. Pat. Nos. 4,969,888 and5,108,404, an expandable body is deployed to form a cavity in cancellousbone tissue, as part of a therapeutic procedure that fixes fractures orother abnormal bone conditions, both osteoporotic and non-osteoporoticin origin. The expandable body compresses the cancellous bone to form aninterior cavity. The cavity receives a filling material, which providesrenewed interior structural support for cortical bone.

[0005] This procedure can be used to treat cortical bone, which due toosteoporosis, avascular necrosis, cancer, or trauma, is fractured or isprone to compression fracture or collapse. These conditions, if notsuccessfully treated, can result in deformities, chronic complications,and an overall adverse impact upon the quality of life.

[0006] A demand exists for alternative systems or methods which, likethe expandable body shown in U.S. Pat. Nos. 4,969,888 and 5,108,404, arecapable of forming cavities in bone and other interior body regions insafe and efficacious ways.

SUMMARY OF THE INVENTION

[0007] The invention provides systems and methods for treating bone.This system comprises a cannula having an axis establishing apercutaneous path leading to inside bone. A shaft is adapted to bedeployed inside bone by movement within and along the axis of thecannula. A cavity forming structure is carried by the shaft andcomprises a surface which directly contacts and shears cancellous bonein response to linear movement of the shaft along the axis of thecannula.

[0008] According to one aspect of the invention, the shaft is flexible.

[0009] According to another aspect of the invention, the surface carriesat least one marker to aid visualizing the cavity forming structureinside bone. In a preferred embodiment, the marker is made from aradiopaque material.

[0010] According to another aspect of the invention, the cavity formingstructure comprises a resilient material, e.g., a resilient metal orresilient plastic material.

[0011] In yet another aspect of the invention, the cavity formingstructure comprises a shape memory material.

[0012] According to another aspect of the invention, an element isprovided to adjust extension of the cavity forming structure beyond theshaft.

[0013] The invention also provides directions for using the systemaccording to a method comprising the steps of providing a cannula havingan axis that establishes a percutaneous path leading to bone, providinga shaft adapted to be deployed inside bone including a cavity formingstructure carried by the shaft comprising a surface which directlycontacts and shears cancellous bone in response to linear movement ofthe shaft along the axis of the cannula, deploying the cannulapercutaneously to establish a path leading to inside bone, introducingthe shaft by movement within and along the axis of the cannula to deploythe cavity forming structure inside bone, and moving the shaft linearlyalong the axis of the cannula to cause the surface to shear cancellousbone and form a cavity. The method for use can also instruct filling thecavity with a material, such as, e.g., bone cement, allograft material,synthetic bone substitute, a medication, or a flowable material thatsets to a hardened condition.

[0014] Features and advantages of the inventions are set forth in thefollowing Description and Drawings, as well as in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a side view of a rotatable tool having a loop structurecapable of forming a cavity in tissue, with the loop structure deployedbeyond the associated catheter tube;

[0016]FIG. 1A is an enlarged end view of the tool shown in FIG. 1;

[0017]FIG. 2 is a side view of the tool shown in FIG. 1, with the loopstructure retracted within the catheter tube;

[0018]FIG. 3 is a side view of the tool shown in FIG. 1, with the loopstructure deployed beyond the catheter tube to a greater extent thanshown in FIG. 1;

[0019]FIG. 4 is a side view of the tool shown in FIG. 1 inserted withina guide sheath for deployment in a targeted treatment area;

[0020]FIG. 5 is a side view of another rotatable tool having a brushstructure capable of forming a cavity in tissue, with the brushstructure deployed beyond the associated drive tube;

[0021]FIG. 5A is an enlarged end view of the tool shown in FIG. 5;

[0022]FIG. 6 is a side view of the tool shown in FIG. 5, with the brushstructure retracted within the drive tube;

[0023]FIG. 7 is a side view of the tool shown in FIG. 5, with the brushstructure deployed beyond the catheter tube to a greater extent thanshown in FIG. 5, and with the brush structure being rotated to cause theassociated bristles to flare outward;

[0024]FIG. 8 is a side view of the tool shown in FIG. 7, with the brushstructure deployed beyond the catheter tube to a greater extent thanshown in FIG. 7, and with the brush structure still being rotated tocause the associated bristles to flare outward;

[0025]FIG. 9 is a side view of an alternative tool having an array ofbristles carried by a flexible shaft, which is capable of forming acavity in tissue;

[0026]FIG. 10 is a side view of the tool shown in FIG. 9 as it is beingdeployed inside a cannula;

[0027]FIG. 11 is the tool shown in FIG. 9 when deployed in a soft tissueregion bounded by hard tissue;

[0028]FIG. 12 is a side view of a tool having a rotatable bladestructure capable of forming a cavity in tissue;

[0029]FIG. 13 is a side view of an alternative curved blade structurethat the tool shown in FIG. 12 can incorporate;

[0030]FIG. 14 is a side view of an alternative ring blade structure thatthe tool shown in FIG. 12 can incorporate;

[0031]FIG. 15 is a side view of the ring blade structure shown in FIG.14 while being introduced through a cannula;

[0032]FIG. 16 is a side view of a rotating tool capable of forming acavity in tissue, with an associated lumen to introduce a rinsing liquidand aspirate debris;

[0033]FIG. 17 is a perspective side view of a tool having a linearmovement blade structure capable of forming a cavity in tissue, with theblade structure deployed beyond the associated catheter tube in anoperative position for use;

[0034]FIG. 18 is an end view of the tool shown in FIG. 17, with theblade structure shown in its operative position for use;

[0035]FIG. 19 is an end view of the tool shown in FIG. 17, with theblade structure shown in its rest position within the catheter tube;

[0036]FIG. 20 is a side view of the tool shown in FIG. 17, with theblade structure shown in its rest position within the catheter tube, asalso shown in an end view in FIG. 18;

[0037]FIG. 21 is a side view of the tool shown in FIG. 17, with theblade structure deployed beyond the associated catheter tube in anoperative position for use, as also shown in an end view in FIG. 18;

[0038]FIG. 22 is a side view of a tool having a linear movement energytransmitter capable of forming a cavity in tissue, with the energytransmitter deployed beyond the associated catheter tube in an operativeposition for use;

[0039]FIG. 23 is a top view of a human vertebra, with portions removedto reveal cancellous bone within the vertebral body, and with a guidesheath located for postero-lateral access;

[0040]FIG. 24 is a side view of the vertebra shown in FIG. 23;

[0041]FIG. 25 is a top view of the vertebra shown in FIG. 23, with thetool shown in FIG. 1 deployed to cut cancellous bone by rotating theloop structure, thereby forming a cavity;

[0042]FIG. 26 is a top view of the vertebra shown in FIG. 23, with thetool shown in FIG. 5 deployed to cut cancellous bone by rotating thebrush structure, thereby forming a cavity;

[0043]FIG. 27 is a side view of the vertebra shown in FIG. 23, with thetool shown in FIG. 17 deployed to cut cancellous bone by moving theblade structure in a linear path, thereby forming a cavity;

[0044]FIG. 28 is a side view of the vertebra shown in FIG. 23, with thetool shown in FIG. 22 deployed to cut cancellous bone using an energytransmitter, which is both rotatable and movable in a linear path,thereby forming a cavity;

[0045]FIG. 29 is a side view of the vertebra shown in FIG. 23, afterformation of a cavity by use of one of the tools shown in FIGS. 25 to28, and with a second tool deployed to introduce material into thecavity for therapeutic purposes;

[0046]FIG. 30 is a plan view of a sterile kit to store a single usecavity forming tool of a type previously shown; and

[0047]FIG. 31 is an exploded perspective view of the sterile kit shownin FIG. 30.

[0048] The invention may be embodied in several forms without departingfrom its spirit or essential characteristics. The scope of the inventionis defined in the appended claims, rather than in the specificdescription preceding them. All embodiments that fall within the meaningand range of equivalency of the claims are therefore intended to beembraced by the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] The systems and methods embodying the invention can be adaptedfor use virtually in any interior body region, where the formation of acavity within tissue is required for a therapeutic or diagnosticpurpose. The preferred embodiments show the invention in associationwith systems and methods used to treat bones. This is because thesystems and methods which embody the invention are well suited for usein this environment. It should be appreciated that the systems andmethods which embody features of the invention can be used in otherinterior body regions, as well.

I. Rotatable Cavity Forming Structures A. Rotatable Loop Structure

[0050]FIG. 1 shows a rotatable tool 10 capable of forming a cavity in atargeted treatment area. The tool 10 comprises a catheter tube 12 havinga proximal and a distal end, respectively 14 and 16. The catheter tube12 preferable includes a handle 18 to aid in gripping and maneuveringthe tube 12. The handle 18 can be made of a foam material secured aboutthe catheter tube 12.

[0051] The catheter tube 12 carries a cavity forming structure 20 at itsdistal end 16. In the illustrated embodiment, the structure 20 comprisesa filament 22 of resilient inert material, which is bent back uponitself and preformed with resilient memory to form a loop.

[0052] The material from which the filament 22 is made can be resilient,inert wire, like stainless steel. Alternatively, resilient injectionmolded inert plastic or shape memory material, like nickel titanium(commercially available as Nitinol™ material), can also be used. Thefilament 22 can, in cross section, be round, rectilinear, or an otherconfiguration.

[0053] As FIG. 1A shows, the filament 22 radiates from slots 24 in abase 26 carried by the distal end 16 of the catheter tube 12. The freeends 28 of the filament 22 extend through the catheter tube 12 and areconnected to a slide controller 30 near the handle 18.

[0054] As FIG. 2 shows, sliding the controller 30 aft (arrow A) retractsthe filament 22 through the slots 24, which progressively decreases thedimensions of the loop structure 20. As FIG. 2 shows, in its farthestaft position, the filament 22 is essentially fully withdrawn and doesnot project a significant distance beyond the distal end 16 of thecatheter tube 12.

[0055] As FIG. 3 shows, sliding the controller 30 forward (arrow F)advances the filament 22 through the slots 24. The loop structure 20forms, which projects beyond the distal end 16 of the catheter tube 12.As it is advanced progressively forward through the slots 24, thedimensions of the loop structure 20 progressively increase (compare FIG.1 to FIG. 3). The controller 30 can include indicia 32, through whichthe physician can estimate the dimensions of the loop structure 20.

[0056] In use (see FIG. 4), the catheter tube 12 is carried for axialand rotational movement within a guide sheath or cannula 34. Thephysician is able to freely slide the catheter tube 12 axially withinthe guide sheath 34 (arrow S in FIG. 4). As FIG. 4 shows, when fullyconfined by the guide sheath 34, the loop structure 20, if projecting asignificant distance beyond the distal end 16, is collapsed by thesurrounding sheath 34. When free of the guide sheath 34, the loopstructure 20 springs open to assume its normal dimension. Thereafter,the physician can operate the controller 30 to alter the dimension ofthe loop structure 20 at will.

[0057] When free of the guide sheath 34, the physician is also able torotate the deployed loop structure 20, by rotating the catheter tube 12within the guide sheath 34 (arrow R in FIG. 4). As will be described ingreater detail alter, rotation of the loop structure 20 slices or cutthrough surrounding tissue mass.

[0058] The materials for the catheter tube 12 are selected to facilitateadvancement and rotation of the loop structure 20. The catheter tube 12can be constructed, for example, using standard flexible, medical gradeplastic materials, like vinyl, nylon, polyethylenes, ionomer,polyurethane, and polyethylene tetraphthalate (PET). The catheter tube12 can also include more rigid materials to impart greater stiffness andthereby aid in its manipulation and torque transmission capabilities.More rigid materials that can be used for this purpose include stainlesssteel, nickel-titanium alloys (Nitinol™ material), and other metalalloys.

[0059] The filament 22 preferably carries one or more radiologicalmarkers 36. The markers 36 are made from known radiopaque materials,like platinum, gold, calcium, tantalum, and other heavy metals. At leastone marker 36 is placed at or near the distal extremity of the loopstructure 20, while other markers can be placed at spaced apartlocations on the loop structure 20. The distal end 16 of the cathetertube 12 can also carry markers. The markers 36 permit radiologicvisualization of the loop structure 20 and catheter tube 12 within thetargeted treatment area.

[0060] Of course, other forms of markers can be used to allow thephysician to visualize the location and shape of the loop structure 20within the targeted treatment area.

B. Rotatable Brush

[0061]FIG. 5 shows an alternative embodiment of a rotatable tool 38capable of forming a cavity in a targeted treatment area. The tool 38comprises a drive shaft 40, which is made from stiffer materials forgood torsion transmission capabilities, e.g., stainless steel,nickel-titanium alloys (Nitinol™ material), and other metal alloys.

[0062] The distal end 42 of the drive shaft carries a cavity formingstructure 44, which comprises an array of filaments forming bristles 46.As FIG. 5A shows, the bristles 46 extend from spaced-apart slots 48 in abase 50 carried by the distal end 42 of the drive shaft 40.

[0063] The material from which the bristles 46 is made can be stainlesssteel, or injection molded inert plastic, or shape memory material, likenickel titanium. The bristles 46 can, in cross section, be round,rectilinear, or an other configuration.

[0064] The proximal end 52 of the drive shaft 40 carries a fitting 54that, in use, is coupled to an electric motor 56 for rotating the driveshaft 40, and, with it, the bristles 46 (arrows R in FIGS. 7 and 8).When rotated by the motor 46, the bristles spread apart (as FIG. 7shows), under the influence of centrifugal force, forming a brush-likestructure 44. The brush structure 44, when rotating, cuts surroundingtissue mass in the targeted treatment area.

[0065] The free ends 58 of the bristles 46 extend through the driveshaft 40 and are commonly connected to a slide controller 60. As FIG. 6shows, sliding the controller 60 aft (arrow A in FIG. 6) shortens thedistance the bristles 46 extend from the base 50. As FIGS. 7 and 8 show,sliding the controller 60 forward (arrow F in FIG. 8) lengthens theextension distance of the bristles 46. Using the controller 60, thephysician is able to adjust the dimension of the cutting area (compareFIG. 7 and FIG. 8).

[0066] The array of bristles 46 preferably includes one or moreradiological markers 62, as previously described. The markers 62 allowradiologic visualization of the brush structure 44 while in use withinthe targeted treatment area. The controller 60 can also include indicia64 by which the physician can visually estimate the bristle extensiondistance. The distal end 42 of the drive shaft 40 can also carry one ormore markers 62.

[0067] The drive shaft 40 of the tool 38 is, in use, carried for axialand rotational movement within the guide sheath or cannula 34, in thesame manner shown for the tool 10 in FIG. 4. The physician is able tofreely slide the drive shaft 40 axially within the guide sheath todeploy it in the targeted treatment area. Once connected to the drivemotor 56, the drive shaft 40 is free to rotate within the guide sheath34 to form the brush structure 44.

[0068]FIG. 9 shows an alternative embodiment of a rotatable tool 138having an array of filaments forming bristles 140, which is capable offorming a cavity in a targeted treatment area. The tool 138 includes aflexible drive shaft 142, which is made, e.g., from twisted wirefilaments, such stainless steel, nickel-titanium alloys (Nitinol™material), and other metal alloys.

[0069] The bristles 140 radially extend from the drive shaft 142, nearits distal end. The bristles 140 can be made, e.g., from resilientstainless steel, or injection molded inert plastic, or shape memorymaterial, like nickel titanium. The bristles 140 can, in cross section,be round, rectilinear, or an other configuration.

[0070] As FIG. 10 shows, the tool 138 is introduced into the targetedtissue region through a cannula 144. When in the cannula 144, theresilient bristles 140 are compressed rearward to a low profile,enabling passage through the cannula. When free of the cannula 144, theresilient bristles 140 spring radially outward, ready for use.

[0071] The proximal end of the drive shaft 142 carries a fitting 146that, in use, is coupled to an electric motor 148. The motor 148 rotatesthe drive shaft 142 (arrow R in FIG. 11), and, with it, the bristles140.

[0072] As FIG. 11 shows, when deployed inside an interior body cavitywith soft tissue S (e.g., cancellous bone bounded by hard tissue H(e.g., cortical bone), the physician can guide the tool 138 through thesoft tissue S by allowing the rotating bristles 140 to ride against theadjoining hard tissue H. The flexible drive shaft 142 bends to followthe contour of the hard tissue H, while the rotating bristles 140 cutadjoining soft tissue S, forming a cavity C.

[0073] In the illustrated embodiment, the drive shaft 142 carries apitched blade 151 at its distal end. The blade 151 rotates with thedrive shaft 142. By engaging tissue, the blade 151 generates aforward-pulling force, which helps to advance the drive shaft 142 andbristles 140 through the soft tissue mass.

[0074] In the illustrated embodiment, the bristles 140, or the cannula144, or both include one or more radiological markers 153, as previouslydescribed. The markers 153 allow radiologic visualization of thebristles 140 while rotating and advancing within the targeted treatmentarea.

C. Rotatable Blade Structure

[0075]FIG. 12 shows an alternative embodiment of a rotatable tool 106capable of forming a cavity in a targeted treatment area. The tool 106,like the tool 38, comprises a generally stiff drive shaft 108, madefrom, e.g., stainless steel, nickel-titanium alloys (Nitinol™ material),and other metal alloys, for good torsion transmission capabilities.

[0076] The distal end of the drive shaft 108 carries a cavity formingstructure 110, which comprises a cutting blade. The blade 110 can takevarious shapes.

[0077] In FIGS. 12 and 13, the blade 110 is generally L-shaped, having amain leg 112 and a short leg 116. In the illustrated embodiment, themain leg 112 of the blade 110 is pitched radially forward of the driveshaft axis 114, at a small forward angle beyond perpendicular to thedrive shaft. The main leg 112 may possess a generally straightconfiguration (as FIG. 12 shows), or, alternatively, it may present agenerally curved surface (as FIG. 13 shows). In the illustratedembodiment, the short leg 116 of the blade 110 is also pitched at asmall forward angle from the main leg 112, somewhat greater thanperpendicular.

[0078] In FIG. 14, the blade 110 takes the shape of a continuous ring126. As illustrated, the ring 126 is pitched slightly forward, e.g., atan angle slightly greater than perpendicular relative to the drive shaftaxis 114.

[0079] The material from which the blade 110 is made can be stainlesssteel, or injection molded inert plastic. The legs 112 and 116 of theblade 110 shown in FIGS. 12 and 13, and the ring 126 shown in FIG. 14,can, in cross section, be round, rectilinear, or an other configuration.

[0080] When rotated (arrow R), the blade 110 cuts a generallycylindrical path through surrounding tissue mass. The forward pitch ofthe blade 110 reduces torque and provides stability and control as theblade 110 advances, while rotating, through the tissue mass.

[0081] Rotation of the blade 110 can be accomplished manually or athigher speed by use of a motor. In the illustrated embodiment, theproximal end of the drive shaft 108 of the tool 106 carries a fitting118. The fitting 118 is coupled to an electric motor 120 to rotate thedrive shaft 108, and, with it, the blade 110.

[0082] As FIG. 15 shows, the drive shaft 108 of the tool 108 is deployedsubcutaneously into the targeted tissue area through a guide sheath orcannula 124. Connected to the drive motor 120, the drive shaft 108rotates within the guide sheath 34, thereby rotating the blade 110 tocut a cylindrical path P in the surrounding tissue mass TM. The blade110 can be advanced and retracted, while rotating, in a reciprocal path(arrows F and A), by applying pushing and pulling forces upon the driveshaft 108. The blade 110 can also be withdrawn into the cannula 124 toallow changing of the orientation of the cannula 124. In this way,successive cylindrical paths can be cut through the tissue mass, throughrotating and reciprocating the blade 110, to thereby create a desiredcavity shape.

[0083] The blade 110, or the end of the cannula 124, or both can carryone or more radiological markers 122, as previously described. Themarkers 122 allow radiologic visualization of the blade 110 and itsposition relative to the cannula 34 while in use within the targetedtreatment area.

D. Rinsing and Aspiration

[0084] As FIG. 16 shows, any of the tools 10, 38, 106, or 138 caninclude an interior lumen 128. The lumen 128 is coupled via a Y-valve132 to a external source 130 of fluid and an external vacuum source 134.

[0085] A rinsing liquid 136, e.g., sterile saline, can be introducedfrom the source 130 through the lumen 128 into the targeted tissueregion as the tools 10, 38, or 106 rotate and cut the tissue mass TM.The rinsing liquid 136 reduces friction and conducts heat away from thetissue during the cutting operation. The rinsing liquid 136 can beintroduced continuously or intermittently while the tissue mass is beingcut. The rinsing liquid 136 can also carry an anticoagulant or otheranti-clotting agent.

[0086] By periodically coupling the lumen 128 to the vacuum source 134,liquids and debris can be aspirated from the targeted tissue regionthrough the lumen 128.

II. Linear Movement Cavity Forming Structures A. Cutting Blade

[0087] FIGS. 17 to 21 show a linear movement tool 66 capable of forminga cavity in a targeted treatment area. Like the tool 10, the tool 66comprises a catheter tube 68 having a handle 70 (see FIG. 20) on itsproximal end 72 to facilitate gripping and maneuvering the tube 68.

[0088] The catheter tube 68 carries a linear movement cavity formingstructure 74 at its distal end 76. In the illustrated embodiment, thestructure 56 comprises a generally rigid blade 78, which projects at aside angle from the distal end 76 (see FIGS. 17 and 21). The blade 78can be formed from stainless steel or cast or molded plastic.

[0089] A stylet 80 is carried by an interior track 82 within thecatheter tube 68 (see FIGS. 18 and 19). The track 82 extends along theaxis of the catheter tube 68. The stylet 80 is free to move in a linearaft path (arrow A in FIG. 20) and a linear forward path (arrow F in FIG.21) within the track 82. The stylet 80 is also free to rotate within thetrack 82 (arrow R in FIG. 17).

[0090] The far end of the stylet 80 is coupled to the blade 78. The nearend of the stylet 80 carries a control knob 84. By rotating the controlknob 84, the physician rotates the blade 78 between an at rest position,shown in FIGS. 19 and 20, and an operating position, shown in FIGS. 17,18, and 21. When in the at rest position, the physician can push or pullupon the control knob 84 to move the blade 78 in a linear path withinthe catheter tube (see FIG. 20). By pushing on the control knob 84, thephysician can move the blade 78 outside the catheter tube 68, where itcan be rotated into the operating condition (see FIG. 21). When in theoperating position, pushing and pulling on the control knob 84 moves theblade in linear strokes against surrounding tissue mass.

[0091] In use, the catheter tube 68 is also carried for sliding androtation within the guide sheath or cannula 34, in the same manner shownin FIG. 4. The physician is able to freely slide the catheter tube 68axially within the guide sheath 34 to deploy the tool 66 in the targetedtreatment site. When deployed at the site, the physician can deploy theblade 78 in the operating condition outside the catheter tube 68 andslide the blade 78 along tissue in a linear path. Linear movement of theblade 78 along tissue cuts the tissue. The physician is also able torotate both the catheter tube 68 within the guide sheath 34 and theblade 78 within the catheter tube 68 to adjust the orientation andtravel path of the blade 78.

[0092] The blade 78 can carry one or more radiological markers 86, aspreviously described, to allow radiologic visualization of the blade 78within the targeted treatment area. Indicia 88 on the stylet 80 can alsoallow the physician to visually approximate the extent of linear orrotational movement of the blade 78. The distal end 76 of the cathetertube 68 can also carry one or more markers 86.

B. Energy Transmitters

[0093]FIG. 22 shows an alternative embodiment of a linear movement tool90 capable of forming a cavity in a targeted treatment area. The tool 90is physically constructed in the same way as the linear movement tool 66just described, so common reference numerals are assigned.

[0094] However, for the tool 90 shown FIG. 22, the far end of the stylet80 carries, not a cutting blade 78, but instead a transmitter 92 capableof transmitting energy that cuts tissue (shown by lines 100 in FIG. 22).A connector 94 couples the transmitter 92 to a source 96 of the energy,through a suitable energy controller 98.

[0095] The type of energy 100 that the transmitter 92 propagates toremove tissue in the targeted treatment area can vary. For example, thetransmitter 92 can propagate ultrasonic energy at harmonic frequenciessuitable for cutting the targeted tissue. Alternatively, the transmitter92 can propagate laser energy at a suitable tissue cutting frequency.

[0096] As before described, the near end of the stylet 80 includes acontrol knob 84. Using the control knob 84, the physician is able tomove the transmitter 92 in a linear path (arrows A and F in FIG. 22)between a retracted position, housed with the catheter tube 68 (like theblade 78 shown in FIG. 20), and a range of extended positions outsidethe catheter tube 68, as shown in FIG. 22).

[0097] As also described before, the catheter tube 68 of the tool 90 is,in use, carried for sliding and rotation within the guide sheath orcannula 34. The physician slides the catheter tube 68 axially within theguide sheath 34 for deployment of the tool 90 at the targeted treatmentsite. When deployed at the site, the physician operates the control knob84 to linearly move and rotate the transmitter 92 to achieve a desiredposition in the targeted treatment area. The physician can also rotatethe catheter tube 68 and thereby further adjust the location of thetransmitter 92.

[0098] The transmitter 92 or stylet 80 can carry one or moreradiological markers 86, as previously described, to allow radiologicvisualization of the position of the transmitter 92 within the targetedtreatment area. Indicia 88 on the stylet 80 can also allow the physicianto visually estimate the position of the transmitter 92. The distal end76 of the catheter tube 68 can also carry one or more markers 86.

III. Use of Cavity Forming Tools

[0099] Use of the various tools 10 (FIGS. 1 to 4), 38 (FIGS. 5 to 8),138 (FIGS. 9 to 11), 106 (FIGS. 12 to 15), 66 (FIGS. 17 to 21), and 90(FIG. 22) will now be described in the context of deployment in a humanvertebra 150.

[0100]FIG. 23 shows the vertebra 150 in coronal (top) view, and FIG. 24shows the vertebra 150 in lateral (side) view. It should be appreciated,however, the tool is not limited in its application to vertebrae. Thetools 10, 38, 138, 106, 66, and 90 can be deployed equally as well inlong bones and other bone types.

[0101] As FIGS. 23 and 24 show, the vertebra 150 includes a vertebralbody 152, which extends on the anterior (i.e., front or chest) side ofthe vertebra 150. The vertebral body 152 includes an exterior formedfrom compact cortical bone 158. The cortical bone 158 encloses aninterior volume of reticulated cancellous, or spongy, bone 160 (alsocalled medullary bone or trabecular bone).

[0102] The vertebral body 152 is in the shape of an oval disk. As FIGS.23 and 24 show, access to the interior volume of the vertebral body 152can be achieved. e.g., by drilling an access portal 162 through a sideof the vertebral body 152, which is called a postero-lateral approach.The portal 162 for the postero-lateral approach enters at a posteriorside of the body 152 and extends at angle forwardly toward the anteriorof the body 152. The portal 162 can be performed either with a closed,minimally invasive procedure or with an open procedure.

[0103] Alternatively, access into the interior volume can beaccomplished by drilling an access portal through either pedicle 164(identified in FIG. 23). This is called a transpedicular approach. It isthe physician who ultimately decides which access site is indicated.

[0104] As FIGS. 23 and 24 show, the guide sheath 34 (earlier shown inFIG. 4) is located in the access portal 162. Under radiologic or CTmonitoring, a selected one of the tools 10, 38, 66, or 90 can beintroduced through the guide sheath 34.

A. Deployment and Use of the Loop Tool in a Vertebral Body

[0105] When, for example, the loop tool 10 is used, the loop structure20 is, if extended, collapsed by the guide sheath 34 (as shown in FIG.4), or otherwise retracted within the catheter tube 12 (as FIG. 2 shows)during passage through the guide sheath 34.

[0106] Referring to FIG. 25, when the loop tool 10 is deployed outsidethe guide sheath 34 in the cancellous bone 160, the physician operatesthe controller 30 in the manner previously described to obtain a desireddimension for the loop structure 20, which can be gauged by radiologicmonitoring using the on-board markers 36. The physician manually rotatesthe loop structure 20 through surrounding cancellous bone 160 (asindicated by arrows R in FIG. 25). The rotating loop structure 20 cutscancellous bone 160 and thereby forms a cavity C. A suction tube 102,also deployed through the guide sheath 34, removes cancellous bone cutby the loop structure 20. Alternatively, the catheter tube 12 caninclude an interior lumen 128 (as shown in FIG. 16) to serve as asuction tube as well as to convey a rinsing liquid into the cavity as itis being formed.

[0107] Synchronous rotation and operation of the controller 30 toenlarge the dimensions of the loop structure 20 during the procedureallows the physician to achieve a create a cavity C of desireddimension. Representative dimensions for a cavity C will be discussed ingreater detail later.

B. Deployment and Use of the Brush Tool in a Vertebral Body

[0108] When, for example, the brush tool 38 is used, the physicianpreferable withdraws the bristles 46 during their passage through theguide sheath 34, in the manner shown in FIG. 6.

[0109] Referring to FIG. 26, when the brush tool 38 is deployed incancellous bone 160 free of the guide sheath 34, the physician advancesthe bristles 46 a desired distance (as shown in FIG. 5), aided byradiologic monitoring of the markers 62, or the indicia 32 previouslydescribed, or both. The physician connects the drive shaft 40 to themotor 56 to rotate the bristles 46, creating the brush structure 44. AsFIG. 26 shows, the rotating brush structure 44 cuts cancellous bone 160and forms a cavity C. The suction tube 102 (or a lumen 128 in the driveshaft 40, as shown in FIG. 16) introduces a rinsing fluid (with ananticoagulant, if desired) and removes cancellous bone cut by the brushstructure 44. By periodically stopping rotation of the brush structure44 and operating the controller 60 (previously described) to increasethe forward extension of the bristles 46, the physician able over timeto create a cavity C having the desired dimensions.

C. Deployment and use of the Linear Tools in a Vertebral Body

[0110] When, for example, one of the linear movement tools 66 or 90 areused, the physician preferable withdraws the blade 78 or the transmitter92 into the catheter tube 68 in the manner shown in FIG. 20, until thedistal end 76 of the catheter tube 68 is free of the guide sheath 34.

[0111] Referring to FIG. 27, using the blade tool 66, the physicianoperates the stylet 80 forward (arrow F) and aft (arrow A) to move theblade 78 in a linear path through cancellous bone 160. The blade 78scrapes loose and cuts cancellous bone 160 along its path, which thesuction tube 102 removes. A cavity C is thereby formed. Synchronousrotation (arrow R) and linear movement (arrows F and A) of the blade 78allow the physician to create a cavity C having a desired dimension.

[0112] Referring to FIG. 28, using the energy transmitting tool 90, thephysician rotates (arrow R) and pushes or pulls upon the stylet 80(arrows F and A) to position the energy transmitter 92 at desiredlocations in cancellous bone 160. The markers 86 aid the locationprocess. Transmission by the transmitter 92 of the selected energy cutscancellous bone 160 for removal by the suction tube 102. A cavity C isthereby formed. Through purposeful maneuvering of the transmitter 92,the physician achieves a cavity C having the desired dimension.

D. Deployment of Other Tools into the Cavity

[0113] Once the desired cavity C is formed, the selected tool 10, 38,66, 90, 106, or 138 is withdrawn through the guide sheath 34. As FIG. 29shows, an other tool 104 can now be deployed through the guide sheath 34into the formed cavity C. The second tool 104 can, for example, performa diagnostic procedure. Alternatively, the second tool 104 can perform atherapeutic procedure, e.g., by dispensing a material 106 into thecavity C, such as, e.g., bone cement, allograft material, synthetic bonesubstitute, a medication, or a flowable material that sets to a hardenedcondition. Further details of the injection of such materials 106 intothe cavity C for therapeutic purposes are found in U.S. Pat. Nos.4,969,888 and 5,108,404 and in copending U.S. patent application Ser.No. 08/485,394, which are incorporated herein by reference.

E. Bone Cavity Dimensions

[0114] The size of the cavity C varies according to the therapeutic ordiagnostic procedure performed.

[0115] At least about 30% of the cancellous bone volume needs to beremoved in cases where the bone disease causing fracture (or the risk offracture) is the loss of cancellous bone mass (as in osteoporosis). Thepreferred range is about 30% to 90% of the cancellous bone volume.Removal of less of the cancellous bone volume can leave too much of thediseased cancellous bone at the treated site. The diseased cancellousbone remains weak and can later collapse, causing fracture, despitetreatment.

[0116] However, there are times when a lesser amount of cancellous boneremoval is indicated. For example, when the bone disease being treatedis localized, such as in avascular necrosis, or where local loss ofblood supply is killing bone in a limited area, the selected tool 10,38, 66, 90, 106, or 138 can remove a smaller volume of total bone. Thisis because the diseased area requiring treatment is smaller.

[0117] Another exception lies in the use of a selected tool 10, 36, 66,90, 106, or 138 to improve insertion of solid materials in definedshapes, like hydroxyapatite and components in total joint replacement.In these cases, the amount of tissue that needs to be removed is definedby the size of the material being inserted.

[0118] Yet another exception lays the use of a selected tool 10, 36, 66,90, 106, or 138 in bones to create cavities to aid in the delivery oftherapeutic substances, as disclosed in copending U.S. patentapplication Ser. No. 08/485,394. In this case, the cancellous bone mayor may not be diseased or adversely affected. Healthy cancellous bonecan be sacrificed by significant compaction to improve the delivery of adrug or growth factor which has an important therapeutic purpose. Inthis application, the size of the cavity is chosen by the desired amountof therapeutic substance sought to be delivered. In this case, the bonewith the drug inside is supported while the drug works, and the boneheals through exterior casting or current interior or exterior fixationdevices.

IV. Single Use Sterile Kit

[0119] A single use of any one of the tools 10, 38, 138, 106, 66, or 90creates contact with surrounding cortical and cancellous bone. Thiscontact can damage the tools, creating localized regions of weakness,which may escape detection. The existence of localized regions ofweakness can unpredictably cause overall structural failure during asubsequent use.

[0120] In addition, exposure to blood and tissue during a single use canentrap biological components on or within the tools. Despite cleaningand subsequent sterilization, the presence of entrapped biologicalcomponents can lead to unacceptable pyrogenic reactions.

[0121] As a result, following first use, the tools may not meetestablished performance and sterilization specifications. The effects ofmaterial stress and damage caused during a single use, coupled with thepossibility of pyrogen reactions even after resterilization, reasonablyjustify imposing a single use restriction upon the tools for deploymentin bone.

[0122] To protect patients from the potential adverse consequencesoccasioned by multiple use, which include disease transmission, ormaterial stress and instability, or decreased or unpredictableperformance, each single use tool 10, 38, 66, 90, 106, or 138 ispackaged in a sterile kit 500 (see FIGS. 30 and 31) prior to deploymentin bone.

[0123] As FIGS. 30 and 31 show, the kit 500 includes an interior tray508. The tray 508 holds the particular cavity forming tool (genericallydesignated 502) in a lay-flat, straightened condition duringsterilization and storage prior to its first use. The tray 508 can beformed from die cut cardboard or thermoformed plastic material. The tray508 includes one or more spaced apart tabs 510, which hold the tool 502in the desired lay-flat, straightened condition.

[0124] The kit 500 includes an inner wrap 512, which is peripherallysealed by heat or the like, to enclose the tray 508 from contact withthe outside environment. One end of the inner wrap 512 includes aconventional peal-away seal 514 (see FIG. 31), to provide quick accessto the tray 508 upon instance of use, which preferably occurs in asterile environment, such as within an operating room.

[0125] The kit 500 also includes an outer wrap 516, which is alsoperipherally sealed by heat or the like, to enclosed the inner wrap 512.One end of the outer wrap 516 includes a conventional peal-away seal 518(see FIG. 31), to provide access to the inner wrap 512, which can beremoved from the outer wrap 516 in anticipation of imminent use of thetool 502, without compromising sterility of the tool 502 itself.

[0126] Both inner and outer wraps 512 and 516 (see FIG. 31) eachincludes a peripherally sealed top sheet 520 and bottom sheet 522. Inthe illustrated embodiment, the top sheet 520 is made of transparentplastic film, like polyethylene or MYLAR™ material, to allow visualidentification of the contents of the kit 500. The bottom sheet 522 ismade from a material that is permeable to EtO sterilization gas, e.g.,TYVEC™ plastic material (available from DuPont).

[0127] The sterile kit 500 also carries a label or insert 506, whichincludes the statement “For Single Patient Use Only” (or comparablelanguage) to affirmatively caution against reuse of the contents of thekit 500. The label 506 also preferably affirmatively instructs againstresterilization of the tool 502. The label 506 also preferably instructsthe physician or user to dispose of the tool 502 and the entire contentsof the kit 500 upon use in accordance with applicable biological wasteprocedures. The presence of the tool 502 packaged in the kit 500verifies to the physician or user that the tool 502 is sterile and hasnot be subjected to prior use. The physician or user is thereby assuredthat the tool 502 meets established performance and sterilityspecifications, and will have the desired configuration when expandedfor use.

[0128] The kit 500 also preferably includes directions for use 524,which instruct the physician regarding the use of the tool 502 forcreating a cavity in cancellous bone in the manners previouslydescribed. For example, the directions 524 instruct the physician todeploy and manipulate the tool 502 inside bone to cut cancellous boneand form a cavity. The directions 524 can also instruct the physician tofill the cavity with a material, e.g., bone cement, allograft material,synthetic bone substitute, a medication, or a flowable material thatsets to a hardened condition.

[0129] The features of the invention are set forth in the followingclaims.

We claim:
 1. A system for treating bone comprising a cannula having anaxis establishing a percutaneous path leading to inside bone, a shaftadapted to be deployed inside bone by movement within and along the axisof the cannula, and a cavity forming structure carried by the shaftcomprising a surface which directly contacts and shears cancellous bonein response to linear movement of the shaft along the axis of thecannula.
 2. A tool according to claim 1 wherein the shaft is flexible.3. A tool according to claim 1 wherein the surface carries at least onemarker to aid visualizing the cavity forming structure inside bone.
 4. Atool according to claim 3 wherein the marker is made from a radiopaquematerial.
 5. A tool according to claim 1 wherein the cavity formingstructure comprises a resilient material.
 6. A tool according to claim 5wherein the resilient material is metal.
 7. A tool according to claim 5wherein the resilient material is plastic.
 8. A tool according to claim1 wherein the cavity forming structure comprises a shape memorymaterial.
 9. A tool according to claim 1 and further including anelement to adjust extension of the cavity forming structure beyond theshaft.
 10. A system according to claim 1 wherein the surface comprises aloop.
 11. A method for treating bone comprising the steps of providing acannula having an axis that establishes a percutaneous path leading toinside bone, providing a shaft adapted to be deployed inside bonethrough the cannula including a cavity forming structure carried by theshaft comprising a surface which directly contacts and shears cancellousbone in response to linear movement of the shaft along the axis of thecannula, deploying the cannula percutaneously to establish a pathleading to inside bone, introducing the shaft by movement within andalong the axis of the cannula to deploy the cavity forming structureinside bone, and moving the shaft linearly along the axis of the cannulato cause the surface to shear cancellous bone and form a cavity.
 12. Asystem according to claim 11 further including the step of filling thecavity with a material.